TNF-α/Stearate Induced H3K9/18 Histone Acetylation Amplifies IL-6 Expression in 3T3-L1 Mouse Adipocytes

Area of Science:

• * Molecular Biology
• * Immunology
• * Obesity Research

Background:

• * Obesity is linked to chronic inflammation and increased Interleukin-6 (IL-6) production in adipose tissue.
• * The precise molecular mechanisms driving IL-6 exacerbation in obesity remain incompletely understood.
• * Tumor necrosis factor-alpha (TNF-α) and stearate are mildly elevated in adipose tissue during obesity.

Purpose of the Study:

• * To investigate the hypothesis that TNF-α and stearate co-treatment synergistically increase IL-6 gene expression and protein production in mouse adipocytes.
• * To elucidate the underlying molecular mechanism involving histone acetylation.

Main Methods:

• * 3T3-L1 mouse preadipocytes were treated with TNF-α, stearate, or a combination of both.
• * IL-6 gene expression was quantified using quantitative real-time PCR (qPCR).
• * IL-6 protein levels were measured by ELISA, and histone acetylation was analyzed via Western blotting and ChIP-qPCR.

Main Results:

• * Co-treatment with TNF-α and stearate significantly elevated IL-6 gene expression (81-fold) and protein production (338 pg/mL) compared to individual treatments.
• * Inhibition of histone acetyltransferases (HATs) reduced IL-6 expression, while TSA-induced acetylation mimicked the synergistic effect.
• * TNF-α/stearate co-stimulation increased histone H3 lysine 9/18 acetylation (H3K9/18Ac) at the IL-6 promoter, creating a permissive state for transcription.

Conclusions:

• * TNF-α and stearate cooperatively enhance IL-6 expression in adipocytes through an H3K9/18Ac-dependent epigenetic mechanism.
• * This synergistic interaction provides a novel mechanistic insight into IL-6 exacerbation in adipose tissue during obesity.
• * Findings highlight a potential therapeutic target for managing obesity-associated inflammation.